Help Identify Unusual Pottery Makers Mark on Bottom of Black Ceramic Vase

by Mary
(Richland, WA USA)

If anyone can help me identify this Makers Mark on the bottom of this black ceramic vase I picked up at an estate sale in Washington State (USA), I would really appreciate it. The person who sold me the vase, said it was old and she couldn't remember the maker.

I have researched everywhere, but to no avail. I would appreciate help identifying this mark. Thanks!